[SCSI] libsas: enforce eh strategy handlers only in eh context

The strategy handlers may be called in places that are problematic for
libsas (i.e. sata resets outside of domain revalidation filtering /
libata link recovery), or problematic for userspace (non-blocking ioctl
to sleeping reset functions).  However, these routines are also called
for eh escalations and recovery of scsi_eh_prep_cmnd(), so permit them
as long as we are running in the host's error handler, otherwise arrange
for them to be triggered in eh_context.

Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>

3 files changed, 130 insertions, 4 deletions

diff --git a/drivers/scsi/libsas/sas_discover.c b/drivers/scsi/libsas/sas_discover.c
index ff497ac76cb4..b031d238eb7b 100644
--- a/drivers/scsi/libsas/sas_discover.c
+++ b/drivers/scsi/libsas/sas_discover.c
@@ -39,6 +39,7 @@ void sas_init_dev(struct domain_device *dev)
 {
         switch (dev->dev_type) {
         case SAS_END_DEV:
+                INIT_LIST_HEAD(&dev->ssp_dev.eh_list_node);
                 break;
         case EDGE_DEV:
         case FANOUT_DEV:
@@ -286,6 +287,8 @@ void sas_free_device(struct kref *kref)
 
 static void sas_unregister_common_dev(struct asd_sas_port *port, struct domain_device *dev)
 {
+        struct sas_ha_struct *ha = port->ha;
+
         sas_notify_lldd_dev_gone(dev);
         if (!dev->parent)
                 dev->port->port_dev = NULL;
@@ -298,6 +301,14 @@ static void sas_unregister_common_dev(struct asd_sas_port *port, struct domain_d
                 sas_ata_end_eh(dev->sata_dev.ap);
         spin_unlock_irq(&port->dev_list_lock);
 
+        spin_lock_irq(&ha->lock);
+        if (dev->dev_type == SAS_END_DEV &&
+            !list_empty(&dev->ssp_dev.eh_list_node)) {
+                list_del_init(&dev->ssp_dev.eh_list_node);
+                ha->eh_active--;
+        }
+        spin_unlock_irq(&ha->lock);
+
         sas_put_device(dev);
 }
 
diff --git a/drivers/scsi/libsas/sas_init.c b/drivers/scsi/libsas/sas_init.c
index 6909fefa32c5..1bbab3d94a20 100644
--- a/drivers/scsi/libsas/sas_init.c
+++ b/drivers/scsi/libsas/sas_init.c
@@ -116,7 +116,9 @@ int sas_register_ha(struct sas_ha_struct *sas_ha)
         set_bit(SAS_HA_REGISTERED, &sas_ha->state);
         spin_lock_init(&sas_ha->lock);
         mutex_init(&sas_ha->drain_mutex);
+        init_waitqueue_head(&sas_ha->eh_wait_q);
         INIT_LIST_HEAD(&sas_ha->defer_q);
+        INIT_LIST_HEAD(&sas_ha->eh_dev_q);
 
         error = sas_register_phys(sas_ha);
         if (error) {
diff --git a/drivers/scsi/libsas/sas_scsi_host.c b/drivers/scsi/libsas/sas_scsi_host.c
index 52d5b0133db0..2e0e779fb3b2 100644
--- a/drivers/scsi/libsas/sas_scsi_host.c
+++ b/drivers/scsi/libsas/sas_scsi_host.c
@@ -460,14 +460,88 @@ struct sas_phy *sas_get_local_phy(struct domain_device *dev)
 }
 EXPORT_SYMBOL_GPL(sas_get_local_phy);
 
+static void sas_wait_eh(struct domain_device *dev)
+{
+        struct sas_ha_struct *ha = dev->port->ha;
+        DEFINE_WAIT(wait);
+
+        if (dev_is_sata(dev)) {
+                ata_port_wait_eh(dev->sata_dev.ap);
+                return;
+        }
+ retry:
+        spin_lock_irq(&ha->lock);
+
+        while (test_bit(SAS_DEV_EH_PENDING, &dev->state)) {
+                prepare_to_wait(&ha->eh_wait_q, &wait, TASK_UNINTERRUPTIBLE);
+                spin_unlock_irq(&ha->lock);
+                schedule();
+                spin_lock_irq(&ha->lock);
+        }
+        finish_wait(&ha->eh_wait_q, &wait);
+
+        spin_unlock_irq(&ha->lock);
+
+        /* make sure SCSI EH is complete */
+        if (scsi_host_in_recovery(ha->core.shost)) {
+                msleep(10);
+                goto retry;
+        }
+}
+EXPORT_SYMBOL(sas_wait_eh);
+
+static int sas_queue_reset(struct domain_device *dev, int reset_type, int lun, int wait)
+{
+        struct sas_ha_struct *ha = dev->port->ha;
+        int scheduled = 0, tries = 100;
+
+        /* ata: promote lun reset to bus reset */
+        if (dev_is_sata(dev)) {
+                sas_ata_schedule_reset(dev);
+                if (wait)
+                        sas_ata_wait_eh(dev);
+                return SUCCESS;
+        }
+
+        while (!scheduled && tries--) {
+                spin_lock_irq(&ha->lock);
+                if (!test_bit(SAS_DEV_EH_PENDING, &dev->state) &&
+                    !test_bit(reset_type, &dev->state)) {
+                        scheduled = 1;
+                        ha->eh_active++;
+                        list_add_tail(&dev->ssp_dev.eh_list_node, &ha->eh_dev_q);
+                        set_bit(SAS_DEV_EH_PENDING, &dev->state);
+                        set_bit(reset_type, &dev->state);
+                        int_to_scsilun(lun, &dev->ssp_dev.reset_lun);
+                        scsi_schedule_eh(ha->core.shost);
+                }
+                spin_unlock_irq(&ha->lock);
+
+                if (wait)
+                        sas_wait_eh(dev);
+
+                if (scheduled)
+                        return SUCCESS;
+        }
+
+        SAS_DPRINTK("%s reset of %s failed\n",
+                    reset_type == SAS_DEV_LU_RESET ? "LUN" : "Bus",
+                    dev_name(&dev->rphy->dev));
+
+        return FAILED;
+}
+
 /* Attempt to send a LUN reset message to a device */
 int sas_eh_device_reset_handler(struct scsi_cmnd *cmd)
 {
-        struct domain_device *dev = cmd_to_domain_dev(cmd);
-        struct sas_internal *i =
-                to_sas_internal(dev->port->ha->core.shost->transportt);
-        struct scsi_lun lun;
         int res;
+        struct scsi_lun lun;
+        struct Scsi_Host *host = cmd->device->host;
+        struct domain_device *dev = cmd_to_domain_dev(cmd);
+        struct sas_internal *i = to_sas_internal(host->transportt);
+
+        if (current != host->ehandler)
+                return sas_queue_reset(dev, SAS_DEV_LU_RESET, cmd->device->lun, 0);
 
         int_to_scsilun(cmd->device->lun, &lun);
 
@@ -486,8 +560,12 @@ int sas_eh_bus_reset_handler(struct scsi_cmnd *cmd)
 {
         struct domain_device *dev = cmd_to_domain_dev(cmd);
         struct sas_phy *phy = sas_get_local_phy(dev);
+        struct Scsi_Host *host = cmd->device->host;
         int res;
 
+        if (current != host->ehandler)
+                return sas_queue_reset(dev, SAS_DEV_RESET, 0, 0);
+
         res = sas_phy_reset(phy, 1);
         if (res)
                 SAS_DPRINTK("Bus reset of %s failed 0x%x\n",
@@ -667,6 +745,39 @@ static void sas_eh_handle_sas_errors(struct Scsi_Host *shost, struct list_head *
         goto out;
 }
 
+static void sas_eh_handle_resets(struct Scsi_Host *shost)
+{
+        struct sas_ha_struct *ha = SHOST_TO_SAS_HA(shost);
+        struct sas_internal *i = to_sas_internal(shost->transportt);
+
+        /* handle directed resets to sas devices */
+        spin_lock_irq(&ha->lock);
+        while (!list_empty(&ha->eh_dev_q)) {
+                struct domain_device *dev;
+                struct ssp_device *ssp;
+
+                ssp = list_entry(ha->eh_dev_q.next, typeof(*ssp), eh_list_node);
+                list_del_init(&ssp->eh_list_node);
+                dev = container_of(ssp, typeof(*dev), ssp_dev);
+                kref_get(&dev->kref);
+                WARN_ONCE(dev_is_sata(dev), "ssp reset to ata device?\n");
+
+                spin_unlock_irq(&ha->lock);
+
+                if (test_and_clear_bit(SAS_DEV_LU_RESET, &dev->state))
+                        i->dft->lldd_lu_reset(dev, ssp->reset_lun.scsi_lun);
+
+                if (test_and_clear_bit(SAS_DEV_RESET, &dev->state))
+                        i->dft->lldd_I_T_nexus_reset(dev);
+
+                sas_put_device(dev);
+                spin_lock_irq(&ha->lock);
+                clear_bit(SAS_DEV_EH_PENDING, &dev->state);
+                ha->eh_active--;
+        }
+        spin_unlock_irq(&ha->lock);
+}
+
 
 void sas_scsi_recover_host(struct Scsi_Host *shost)
 {
@@ -709,6 +820,8 @@ out:
         if (ha->lldd_max_execute_num > 1)
                 wake_up_process(ha->core.queue_thread);
 
+        sas_eh_handle_resets(shost);
+
         /* now link into libata eh --- if we have any ata devices */
         sas_ata_strategy_handler(shost);